Injection device

ABSTRACT

An injection device includes a syringe having a body with a piston disposed therein with an open end along with a viscous fluid disposed in the body for injection by the piston. A needle assembly is provided which includes a cannula, for example a blunt tipped cannula, having a luer connection engageable with the syringe distal end with the luer connector including a hub. Mating engagement is provided by way of internal threads at the syringe distal end and external treads of a hub with a pitch sufficient to prevent detachment of the hub from the syringe distal end during ejection of the viscous fluid. In addition, a stepped cavity, disposed in the hub, further prevents detachment of the hub from the syringe distal end during ejection of the viscous fluid.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/629,480, filed on Dec. 2, 2009, which claims the benefit ofU.S. Provisional Patent Application No. 61/119,298, filed on Dec. 2,2008 and U.S. Provisional Patent Application No. 61/139,430, filed onDec. 19, 2008, the entire disclosure of each of these applications beingincorporated herein by this specific reference.

BACKGROUND

The present invention is generally directed to non-surgical devices forthe correction of skin contour defects and aging and is moreparticularly directed to an injection device for enabling introductionof a dermal filler into peripheral locations of a human body through acannula.

Dermal fillers such as, such as Juvederm™, a hyaluronic acid basedformulation, have been used for the treatment of nasal labial folds, lipaugmentation, tear troughs, and for facial volumizing through the use ofvery fine syringe needles.

The dermal fillers are of high viscosity and this provides foreffective, and preferably substantially uniform, suspension of thedermal filler into a peripheral location.

A relatively small needle size, gauge, is preferred for delivery of thedermal filler in order to lessen complications and recovery time.However, in combination with the relatively high viscosity of the dermalfiller, a problem can arise with regard to needle assembly separationfrom the syringe due to the high pressure generated by a piston reactingon the high viscosity dermal filler in order to eject the filler fromthe syringe through a fine needle and into the patient.

The present invention overcomes this problem by providing an ejectiondevice which eliminates, or substantially reduces, the probability ofneedle assembly/syringe separation during a procedure.

SUMMARY OF THE INVENTION

An injection device in accordance with the present invention generallyincludes a syringe having a body with a piston disposed therein and anopen distal end.

A needle assembly is provided which includes a cannula and a luerconnector engagable with the syringe distal end. The needle or cannula,hereinafter “cannula”, has a gauge of about 18 to a gauge of about 25 orgreater. The luer connector includes a hub with a distal end supportingthe cannula and a proximal end matable with the syringe distal end.

In one embodiment, the present invention further includes a viscousfluid, for example, a hyaluronic acid-based dermal filler, disposed inthe syringe's body and which is injectable by the piston into aperipheral location of a human or animal body through the cannula.

The mating engagement, for example, between the hub and the syringedistal end is provided by internal threads disposed in the syringedistal end and external threads disposed on the hub, as well as betweena tapered syringe cone and a tapered inside surface of the hub. Theinternal threads have a pitch which is sufficient to prevent detachmentof the hub from syringe distal end during injection of the viscous fluidinto a peripheral location of a human or animal body.

More particularly, in one embodiment, the internal threads have a pitchof between about 2 mm and about 5 mm. For example, the internal threadshave a pitch of about 3 mm. The internal thread may be double lead screwthreads. In addition, the external threads disposed on the hub furthermay also be double lead screw threads and the double lead screw threadsprovide an advantage of enabling the hub to travel twice the distanceinto mating engagement with the syringe distal end with each single turnof the hub. In other embodiments, the internal threads have a pitch ofabout 2.0 mm, about 3.0 mm, about 3.5 mm, about 4 mm, about 4.5 mm orabout 5 mm. In addition, the external threads may have a pitch of about2.0 mm, about 3.0 mm, about 3.5 mm, about 4 mm, about 4.5 mm or about 5mm.

In a specific embodiment, the external threads comprise singlecircumference double lead screw threads as will be hereinafter describedin greater detail.

In addition, a cavity, for example, a stepped cavity, is disposed in thehub. The cavity serves not only reduces dead space in the syringe butalso significantly reduces the possibility of detachment of the hub fromthe syringe distal end during operation of the piston to eject theviscous fluid through the cannula. Thus, the cavity can be considered ahub retention cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will be betterunderstood by the following description when considered in conjunctionwith the accompanying drawings in which:

FIG. 1 is an illustration of use of an injection device in accordancewith the present invention for injecting a viscous fluid into aperipheral location of the human, generally showing a syringe having abody with a piston and a needle assembly;

FIG. 2 is a cross sectional view of the syringe shown in FIG. 1illustrating more clearly showing the syringe body along with a needleassembly with a luer connector engagable with a distal end of thesyringe along with a viscous fluid disposed in the syringe body;

FIG. 3 is an enlarged cross sectional view of the mating engagementbetween a luer connector hub and a distal end of the syringespecifically illustrating internal threads disposed in the syringedistal end and external threads along the hub for enabling the matingengagement, along with a cavity disposed in the hub configured as a hubretention cavity.

FIG. 4 is end view of the hub illustrating double lead screws;

FIG. 5 is an enlarged cross section view of the needle assembly and anopen distal end of the syringe body showing a tapered syringe coneengageable with a tapered inside surface of the needle assembly hub;

FIG. 6 is a cross-section view of the needle assembly engaged with thesyringe's open distal end; and

FIG. 7 is a cross-section view of another embodiment of the invention inwhich the needle assembly includes a cannula with a blunt tip and a sideaperture.

DETAILED DESCRIPTION

With reference to FIG. 1, there is shown an injection device 10 inaccordance with the present invention having a syringe 12 with a body 14with a piston 18 disposed therein.

With additional reference to FIGS. 2 and 3, the syringe 14 includes anopen distal end 22, and a needle assembly 26. The needle assemblyincludes a cannula 30 along with a sheath 34 and a luer connector 38engagable with the syringe open distal end 22, which includes a hub 42having a distal end 46 and a proximal end 50 matable with the syringedistal end 22.

Internal threads 52, 54 and external threads 56, 58 enable the matingengagement. Pitch (P) of the threads 52, 54 enables the ejection ofviscous fluid 62 through the cannula 30 upon operation of the piston 18without separation of the hub 42 from the syringe open distal end 22during ejection of the viscous fluid 62 as illustrated in FIG. 1.

In some embodiments, the viscous fluid 62 is a dermal filler. In someembodiments, the viscous fluid is a hyaluronic acid-based fluid having aviscosity between about 50,000 cps and about 500,000 cps, measured atabout 25° C. with a controlled stress rheometer (RS600 TA Instrument)and a cone plate geometry (40 mm, 2°). In some embodiments, the viscousfluid is a hyaluronic acid based dermal filler having a viscositygreater than about 130,000 cps.

When measured with a traction column test (Versatest, Mecmesin), at 13mm/min (extrusion speed) and a needle with a gauge between 21G to 32G,the viscous fluid may have an extrusion force of between about 5N up toabout 200N, more specifically, an extrusion force of between about 10Nto about 150N.

In an exemplary embodiment, the pitch of the hub threads 56, 58 isbetween about 2 mm and about 5 mm. Preferably, the pitch is about 3 mm.The threads 52, 54 and 56, 58 are preferably at least double lead screwthreads, although triple, and even quadruple lead threads may used. Asmost clearly shown in FIG. 4, in one particular embodiment, the threads56, 58 have two thread starts 66, 68 at a 180° radial displacement fromone another.

As hereinabove noted, this enables rapid engagement of the hub 42 withthe syringe open distal end 22.

In one embodiment, the hub 42 is formed from a low elasticity material,for example, an acrylic or a polycarbonate, rather than polypropylenetypically used for syringe hubs, as hereinafter described in connectionwith needle retention tests. This may further enhance the prevention ofdetachment of the hub 46 from the syringe open distal end 22.

With reference to FIGS. 5 and 6, hub 42 includes a hub retention cavity80 defined by an inside surface 84, for example, a stepped interiorsurface, of the hub 42. For example, the inside surface 84 of the hub 42may include a step 88. This configuration leads to a reduced space,sometimes referred to herein as a “reduced dead space” between theinterior surface of the hub 42 and the distal connecting end of asyringe, relative to a conventional hub without the step configuration.It is believed that this configuration is effective, at least in part,to prevent detachment of said hub from the syringe distal end duringejection of a viscous fluid from the cannula outlet when the hub isengaged to the syringe distal end.

When torqued to the syringe and maximally seated as shown in FIG. 6, atapered syringe cone 90 stops short of the step 88 and creates a deadspace 92 which is reduced by the provision of step 88. Engagementbetween the cone 90 and inside surface 84, which is also tapered,provides a seal therebetween. Low dead space reduces the amount of fluidthat cannot be administered. This is important in that the fluids to beadministered, by injection, often are very expensive.

The step 88 unexpectedly prevents or substantially reduces thepossibility of detachment of the hub 42 from the syringe cone 90 andsyringe open distal end 22 during injection of the viscous fluid 62.

That is, the average detachment force is significantly greater with thestep 88 formed in the cavity hub retention cavity 80 of the hub 42 aswas discovered during comparison study as follows:

Test methods used in this study utilized equipment designed by OmnicaCorporation specifically for torque setting and detachment testing.

The torque set unit utilizes a numerically controlled motor and torquesensor which tightens the needle hub 42 onto the syringe open distal end22 and a pre-determined torque setting testing is shown that the staticfriction between the needle hub 42 and the syringe open distal end 22materials causes more overshoot than observed with standardpolypropylene hubs (not shown).

A detachment tester utilizes a numerically controlled motor drivinglinear carriage against a forced transducer.

In a comparison test, all of the hubs (not shown) were attached to thesyringe open distal end 22 and cone 90 with a torque of 0.07 Nm (Newtonmeter). All of the tests were performed on 0.8 cc syringes havingidentical dimensions, for example, syringe open distal end 22 having anentry diameter D (see FIG. 6), of about 4 mm.

The results are shown in Table 1 for nominal torque static test needleretention with various design attribute combinations.

Table 1 shows that the conventional polypropylene hub mated to a syringewith 5 mm threads has an average detachment force 46.1 N (Newton) whenthe hub is attached to the syringe with a force of 0.07 Nm.

TABLE 1 Nominal torque Static Test Needle Retention with Various DesignAttribute Combinations Average Detachment Needle Design Force (N)¹ @0.07 Nm Conventional Polypropylene Hub, Syringe 46.1 with 5 mm ThreadsConventional Polypropylene Hub, Syringe 56.2 with 3 mm ThreadsPolycarbonate Hub and Syringe with 5 mm 83.2 Threads Polycarbonate Huband Syringe with 3 mm 96.0 Threads Polycarbonate Hub and Syringe with 3mm 200+  Threads and Stepped Cavity

Slight improvement shown in the conventional polypropylene hub attachedto the syringe body with 3 mm threads, and an average detachment forceof about 56.2 N.

Utilizing polycarbonate instead of polypropylene for the hub 42 resultsin an average detachment force of 83.2 N with 5 mm threads utilized forattachment.

Combination of polycarbonate hub 42 with 3 mm threads without a step 88results in a 96 N average detachment force.

Surprisingly, the detachment force for the hub 42 with 3 mm threadsincorporating the dead space reducing step 88 results in an averagedetachment force of more than 200 N.

It is contemplated that other structures may be useful in reducing deadspace in a manner effective to increase detachment force relative toconventional syringe/needle combinations. For example, it iscontemplated that reduced dead space can be accomplished, within thescope of the present invention, by reducing an outer diameter of thesyringe luer tip, increasing an inner diameter of the hub cavity, and/orother ways effective to increase the engagement length of the syringetip and the hub.

Example

A multi-center, double-blind, randomized parallel-controlled prospectivecomparison study was undertaken to test needle disengagement rates. Thisstudy tested needle disengagement rates of a Polycarbonate Hub andSyringe with 3 mm Threads and Stepped Cavity in accordance with thepresent invention (study device) in comparison to a conventionalpolypropylene hub and syringe with 5 mm threads (conventional device).Needles of each of the conventional devices and the study devices testedwere all 30 G×½″ needles. The material injected for the study wasJuvederm™ Ultra Injectable Gel (dermal filler).

There were up to 288 study participants. Each study participantunderwent treatment for improving his or her bilateral nasolabial foldsusing 2 syringes of dermal filler packaged in either the conventionaldevice or the study device.

The results demonstrated a significant difference in needledisengagement rates between the conventional device and the studydevice. No disengagements were reported for the study device. Between 3%and 7% of the needles of the conventional device unintentionallydisengaged during injection.

It is to be appreciated that needles other than traditional sharp-tippedhypodermic type needles such as that shown in FIGS. 1-6 may make upsuitable components of the present needle assemblies. For example,turning now to FIG. 7, a needle assembly 126 in accordance with anotherembodiment of the invention is shown. The needle assembly 126 may beidentical to needle assembly 26 described and shown elsewhere herein,with like elements being represented by like numbers increased by 100.Needle assembly 126 includes hub 142 and hub retention cavity 180defined by an inside surface 184 of the hub 142 and a step 188, thusproviding a unique stepped interior surface and reduced dead space.Instead of sharp-tipped needle 30, a blunt-tipped cannula 98 isprovided. Cannula 98 includes a relatively rounded tip 99 and an outlet,for example, a side aperture 101, space apart from the tip 99. Thepresently described hub 142, by being advantageously structured toresist “pop-off” even under high extrusion forces, enables injection ofviscous fluids, for example, dermal fillers, from a relatively fine,narrow cannula 98. For example, in some embodiments, the cannula 98 hasa gauge greater than 21, greater than 25, greater than 30 and in someembodiments, the cannula has a gauge of up to about 32.

Needle assembly 126 may be used to inject dermal fillers in any suitablemanner known to those of skill in the art.

Although there has been hereinabove described a specific injectiondevice in accordance with the present invention for the purpose ofillustrating the manner in which the invention may be used to advantage,it should be appreciated that the invention is not limited thereto. Thatis, the present invention may suitably comprise, consist of, or consistessentially of the recited elements. Further, the inventionillustratively disclosed herein suitably may be practiced in the absenceof any element which is not specifically disclosed herein. Accordingly,any and all modifications, variations or equivalent arrangements whichmay occur to those skilled in the art, should be considered to be withinthe scope of the present invention as defined in the appended claims.

1. A injection device comprising: a needle assembly comprising a cannulaand a luer connector engageable with a distal end of a syringe, saidcannula having a rounded distal tip and an outlet spaced apart from saidtip, and said luer connector comprising a hub with a distal endsupporting said cannula and a proximal end mateable with the syringedistal end; a cavity, defined by a stepped interior surface of the hub,effective to prevent detachment of said hub from the syringe distal endduring ejection of a viscous fluid from the cannula outlet when the hubis engaged to the syringe distal end; and external threads disposed onan exterior surface of said hub enabling mating engagement between thehub and the syringe distal end.
 2. The device of claim 1 wherein thestepped cavity provides a reduced dead space relative to an otherwiseidentical needle assembly without the stepped interior surface.
 3. Thedevice according to claim 1 wherein the external threads has a pitch ofabout 3 mM.
 4. The device according to claim 3 wherein the externalthreads comprise double lead screw threads.
 5. The device according toclaim 4 wherein the external threads comprise single circumferencedouble lead screw threads.
 6. The injection device of claim 7 whereinthe cannula has a gauge greater than
 21. 7. The injection device ofclaim 1 wherein the cannula has a gauge greater than
 25. 8. Theinjection device of claim 1 wherein the cannula has a gauge greater than30.
 9. The injection device of claim 1 wherein the cannula has a gaugeof up to about
 32. 10. An injection device comprising: a syringe havinga body with a piston disposed therein and a distal end; a needleassembly comprising a cannula and a luer connector engageable with thesyringe distal end, said cannula having a rounded distal tip and anoutlet spaced apart from said tip, and said luer connector comprising ahub with a distal end supporting said cannula and a proximal endmateable with the syringe distal end; a cavity, defined by a steppedinterior surface of the hub, effective to prevent detachment of said hubfrom the syringe distal end during ejection of a viscous fluid from thecannula outlet when the hub is engaged to the syringe distal end; andexternal threads disposed on an exterior surface of said hub enablingmating engagement between the hub and the syringe distal end.
 11. Theinjection device of claim 10 wherein the cannula has a gauge greaterthan
 21. 12. The injection device of claim 10 wherein the cannula has agauge greater than
 25. 13. The injection device of claim 10 wherein thecannula has a gauge greater than
 30. 14. The injection device of claim10 wherein the cannula has a gauge of up to about
 32. 15. The injectiondevice of claim 10 further comprising viscous fluid disposed in saidbody and injectable by said piston through said cannula.
 16. Theinjection device of claim 15 wherein the fluid is a dermal filler. 17.The injection device of claim 10 further comprising internal threadsdisposed in the syringe distal end enabling mating engagement of the hubexternal threads and the syringe distal end.
 18. The injection device ofclaim 10 wherein the external threads have a pitch of about 3 mM. 19.The device according to claim 10 wherein the external threads comprisedouble lead screw threads.
 20. The device according to claim 10 whereinthe external threads comprise single circumference double lead screwthreads.